diff --git a/src/configure b/src/configure
index 1910dc4bf3..d86f3205a3 100755
--- a/src/configure
+++ b/src/configure
@@ -606,7 +606,7 @@ nextstep*) os=nextstep;;
    exit;;
 esac
 
-if test $need_tas = "yes"
+if test "X$need_tas" = "Xyes"
 then
 	
 	TAS=tas.o
diff --git a/src/configure.in b/src/configure.in
index 16e475c11c..c8877a5818 100644
--- a/src/configure.in
+++ b/src/configure.in
@@ -42,7 +42,7 @@ nextstep*) os=nextstep;;
    exit;;
 esac
 
-if test $need_tas = "yes"
+if test "X$need_tas" = "Xyes"
 then
 	AC_LINK_FILES(backend/port/tas/${os}.s, backend/port/tas.s)
 	TAS=tas.o